Spherical joints, wherein a pair of members are connected together for compound movements by a semi-spherical bearing having a journal mounted therein, are normally sealed by a pair of annular seal assemblies disposed on either side of the journal. Sealing of the joint is particularly important in application of the joint to construction vehicles, such as the pivotal joint connecting each end of an equalizer bar to a track roller frame of a track-type vehicle. During operation of the vehicle in the heavy dust-laden environments, the transversely disposed equalizer bar and track roller frame will be subjected to relative rotational movement about a journal pin of the joint and pivotal movement transverse to such rotational movement.
It is during this latter pivotal movement that the seal assemblies are subjected to tensile and compressive forces which tend to curtail the service life of the seal assemblies. Seal assemblies of this type are illustrated in FIG. 4 of the drawings with each seal assembly comprising a pair of radially disposed retaining rings having an elastomeric seal compressed therebetween. In addition to being subjected to tensile and compressive forces during pivotal movement P", the elastomeric seals are subjected to torsional stresses when relative rotational movement occurs between the equalizer bar and track roller frame.
Furthermore, the relatively tall cross-section of the seal tends to make it difficult to incorporate the seal assembly in certain designs wherein space limitations are critical. Also, conventional seal assemblies of this type are expensive to manufacture and install, as well as service, due to their swaged construction and the inability to employ modern manufacturing techniques, such as injection molding, for the fabrication of the elastomeric seal. Limitations are also placed on the design of the journal since the inner retaining ring of the seal assembly is press-fitted onto the pin. The rather severe operating forces imposed on the elastomeric seal further dictate the need for a relatively soft elastomeric composition for the seal, such as Neoprene, which must be precompressed to enable the seal assembly to counteract high stresses imposed thereon.
The present invention is directed to overcoming one or more of the problems as set forth above.